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Commit 2ab455cc authored by Anthony Liguori's avatar Anthony Liguori Committed by Avi Kivity
Browse files

KVM: VMX: Add lazy FPU support for VT 



Only save/restore the FPU host state when the guest is actually using the
FPU.

Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 25c4c276

drivers/kvm/vmx.c

+56 −5
Original line number Diff line number Diff line
@@ -101,6 +101,13 @@ static inline int is_page_fault(u32 intr_info) 
		(INTR_TYPE_EXCEPTION | PF_VECTOR | INTR_INFO_VALID_MASK);

}



static inline int is_no_device(u32 intr_info)

{

	return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK |

			     INTR_INFO_VALID_MASK)) ==

		(INTR_TYPE_EXCEPTION | NM_VECTOR | INTR_INFO_VALID_MASK);

}



static inline int is_external_interrupt(u32 intr_info)

{

	return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK))
@@ -216,6 +223,16 @@ static void vmcs_write64(unsigned long field, u64 value) 
#endif

}



static void vmcs_clear_bits(unsigned long field, u32 mask)

{

	vmcs_writel(field, vmcs_readl(field) & ~mask);

}



static void vmcs_set_bits(unsigned long field, u32 mask)

{

	vmcs_writel(field, vmcs_readl(field) | mask);

}



/*

 * Switches to specified vcpu, until a matching vcpu_put(), but assumes

 * vcpu mutex is already taken.
@@ -833,6 +850,11 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) 
	}

#endif



	if (!(cr0 & CR0_TS_MASK)) {

		vcpu->fpu_active = 1;

		vmcs_clear_bits(EXCEPTION_BITMAP, CR0_TS_MASK);

	}



	vmcs_writel(CR0_READ_SHADOW, cr0);

	vmcs_writel(GUEST_CR0,

		    (cr0 & ~KVM_GUEST_CR0_MASK) | KVM_VM_CR0_ALWAYS_ON);
@@ -842,6 +864,12 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) 
static void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)

{

	vmcs_writel(GUEST_CR3, cr3);



	if (!(vcpu->cr0 & CR0_TS_MASK)) {

		vcpu->fpu_active = 0;

		vmcs_set_bits(GUEST_CR0, CR0_TS_MASK);

		vmcs_set_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR);

	}

}



static void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
@@ -1368,6 +1396,15 @@ static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
		asm ("int $2");

		return 1;

	}



	if (is_no_device(intr_info)) {

		vcpu->fpu_active = 1;

		vmcs_clear_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR);

		if (!(vcpu->cr0 & CR0_TS_MASK))

			vmcs_clear_bits(GUEST_CR0, CR0_TS_MASK);

		return 1;

	}



	error_code = 0;

	rip = vmcs_readl(GUEST_RIP);

	if (intr_info & INTR_INFO_DELIEVER_CODE_MASK)
@@ -1556,7 +1593,11 @@ static int handle_cr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
		break;

	case 2: /* clts */

		vcpu_load_rsp_rip(vcpu);

		set_cr0(vcpu, vcpu->cr0 & ~CR0_TS_MASK);

		vcpu->fpu_active = 1;

		vmcs_clear_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR);

		vmcs_clear_bits(GUEST_CR0, CR0_TS_MASK);

		vcpu->cr0 &= ~CR0_TS_MASK;

		vmcs_writel(CR0_READ_SHADOW, vcpu->cr0);

		skip_emulated_instruction(vcpu);

		return 1;

	case 1: /*mov from cr*/
@@ -1806,8 +1847,14 @@ static int vmx_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
	if (vcpu->guest_debug.enabled)

		kvm_guest_debug_pre(vcpu);



	if (vcpu->fpu_active) {

		fx_save(vcpu->host_fx_image);

		fx_restore(vcpu->guest_fx_image);

	}

	/*

	 * Loading guest fpu may have cleared host cr0.ts

	 */

	vmcs_writel(HOST_CR0, read_cr0());



#ifdef CONFIG_X86_64

	if (is_long_mode(vcpu)) {
@@ -1965,8 +2012,11 @@ static int vmx_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
	}

#endif



	if (vcpu->fpu_active) {

		fx_save(vcpu->guest_fx_image);

		fx_restore(vcpu->host_fx_image);

	}



	vcpu->interrupt_window_open = (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0;



	asm ("mov %0, %%ds; mov %0, %%es" : : "r"(__USER_DS));
@@ -2078,6 +2128,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu) 
	vmcs_clear(vmcs);

	vcpu->vmcs = vmcs;

	vcpu->launched = 0;

	vcpu->fpu_active = 1;



	return 0;